ABSTRACT

The Mount Rogers Formation is a thick (3,000 m) succession of late Precambrian sedimentary and volcanic rocks exposed along the northwestern flank of the Blue Ridge anticlinorium in southwestern Virginia. Probable contemporaneous equivalents include the Ocoee Series of Tennessee, the Grandfather Mountain and Ashe Formations of North Carolina, and the Swift Run and Lynchburg Formations of central Virginia. The upper third of the Mount Rogers Formation includes a wide range of rocks which, on the basis of sedimentary structures, composition, and texture are interpreted as glacial till, fluvial channel conglomerate, (varved?) lacustrine or shallow marine siltstone and shale (rhythmites), turbidite sandstone, and ice rafted pebbly mudstone. These rock types were deposited on piedmont fans and across braided floodplain areas which flanked an uplifted highland complex composed of igneous and metamorphic rocks that today constitute the Blue Ridge Basement Complex. Lakes or a shallow marine embayment lay further east in the area where the present core of the Blue Ridge anticlinorium is located. The depositional area of the Mount Rogers Formation may have originated during the early stages of rifting which preceded the opening of the Paleozoic Protoatlantic Ocean.